Dave,
I have a YS 63 about 2 years old. I've run about 10 8oz tanks of Cool Power 30% heli fuel through it and the last two outings have resulted in dead sticks. After the first troubled outing, I took out the fuel tank and noticed that the stopper to the tank was not tight. So I fixed that and then when I took it out yesterday, I got in 1 flight with no problems, 2nd flight engine quit upon landing, third flight engine quit on takeoff. I pulled the fuel tank out again but this time the stopper was good & tight.

There is plenty of smoke during flight, so I don't think it's lean. Any ideas? [][&:]

Thanks,
Bruce